There is an increasing need for safe and effective antiviral agents for prevention and treatment of existing and emerging life threatening viral diseases.
DNase I inhibits synthesis and replication of viral double-stranded (ds) DNA in cells infected with vaccinia virus, human herpes virus, cytomegalovirus and adenovirus without affecting synthesis of cellular genomic DNA and integrity of the treated cells (Trukhachev and Salganik, Virology 33, 552, 1967; Salganik et al., Dokl. Akad. Nauk SSSR (Proc. USSR Acad. Sci.) 180: 1473-1476, 1968; Lapik, et al., Pharmac. Toxicol. 2: 210, 1970; Salganik, Current Trends in Life Sciences, 12: 115-119, 1984). Bovine pancreatic RNase A has been shown to inhibit viral replication in cells infected with influenza, tick-born encephalitis and poliomyelitis and viruses (LeClerc, Nature 177:578-579 (1956); Salganik, Current Trends in Life Sciences, 12: 115-123, 1984). Therapeutic activity of native bovine pancreatic DNase I against human herpes and adenoviruses and bovine pancreatic RNase A against tick-borne encephalitis and influenza viruses have been demonstrated in clinical trials (Salganik et al., Nature 214, 100, 1967; Gutarov et al., Zhurn. Nevropath. Psychiatry. 11, 75-78, 1976; Glukhov et al., Arch. Neurol. 33: 598-603, 1976). Bovine pancreatic DNase I directed against dsDNA-parvovirus combined with the bovine pancreatic RNase A directed against ssRNA-paramixovirus have been shown effective in treatment of dogs infected by both viruses (U.S. Pat. No. 5,484,589 to Salganik).
Certain RNases such as cytotoxic Onconase® isolated from oocytes and embryos of Northern Leopard Frog (Rana pipiens) and bovine seminal RNase A (BS-RNase) have been shown also to moderately inhibit replication of HIV-I in cell culture (Youle, et al., Proc. Natl. Acad. Sci. USA 91, No. 13: 6012-6016, 1994; Saxena, et al. J. Biol. Chem. 271: 20783-20788, 1996; Huang, et al., Proc. Natl. Acad. Sci. USA 96: 2678-2681, 1999).
These studies of antiviral properties of native bovine pancreatic DNase I and RNase A do not address the shortcomings of native nucleases such as high susceptibility to endogenous proteolytic degradation, low cellular uptake, short half-life and others. Further, those studies, do not address major issues for antiviral therapeutics such as a likelihood development of viral resistance during treatment by nucleases.
The earlier approach to utilizing hydrolytic properties of DNase I and RNase A against viral nucleic acids was limited to targeting double-stranded viral genomic DNA or single-stranded viral genomic RNA within infected cells, however multiple forms of intermediate viral nucleic acids such as linear, circular or super-coiled dsDNA, ssDNA, dsRNA or ssRNA as well as hybrid RNA-DNA, which appear in the course of the replication cycle of targeted viruses were not considered.